This invention relates to an ink jet printhead. More particularly, the invention relates to a Nozzle Poker for Moving Nozzle Ink Jet.
Most ink jet printheads of the type manufactured using micro-electro mechanical systems (MEMS) technology have been proposed in a construction using nozzle chambers formed in MEMS layers on the top of a substrate with nozzle chambers formed in the layers. Each chamber is provided with a movable paddle actuated by some form of actuator to force ink in a drop through the nozzle associated with the chamber upon receipt of an electrical signal to the actuator. Such a construction is typified by the disclosure in my International Patent Application PCT/AU99/00894.
The present invention stems from the realisation that there are advantages to be gained by dispensing with the paddles and causing ink drops to be forced from the nozzle by decreasing the size of the nozzle chamber. It has been realised that this can be achieved by causing the actuator to move the nozzle itself downwardly in the chamber thus dispensing with the paddle, simplifying construction and providing an environment which is less prone to the leakage of ink from the nozzle chamber.
According to the invention there is provided An ink jet printhead including:
a plurality of nozzles each adapted to eject drops of ink toward a surface to be printed; wherein,
each of the nozzles has an actuator operatively connected to an apertured roof portion such that the actuator moves the roof portion away from the surface to be printed to eject the ink; wherein,
a projection within the nozzle is configured to extend through an aperture in the roof portion when the roof portion moves away from the surface to eject the ink.
Preferably, each of the nozzles further includes an associated nozzle chamber adapted to be supplied with ink via at least one conduit in an underlying substrate.
Preferably, the roof portion has a sidewall depending from its periphery to telescopically engage a peripheral sidewall extending from an opposing floor portion to define the nozzle chamber.
Preferably, said projection is an elongate poker member, the free end of the poker member being positioned to protrude at least into the aperture in said nozzle when the roof portion is moved downwardly by the actuator.
Preferably, the free end of the poker member protrudes through the aperture in said nozzle when the roof portion is moved downwardly by the actuator.
Preferably, the poker member is an elongate upwardly extending pin, supported by the floor member.
Preferably, the conduit in the underlying substrate communicates with the nozzle chamber through an opening in the floor portion, and wherein the lower end of the elongate pin is supported on a bridge member extending across said opening.